Biological sciences

Changes in quinone profiles of hot spring microbial mats with a thermal gradient

Article Abstract:

Changes in quinone profiles are used in studying the microbial mat communities in sulfide-containing neutral-pH hot springs from different geographical areas in Japan. Quinone profiling is used in distinguishing the various respiratory and photosynthetic quinones in microbial cells and in estimating the microbial redox states. Results reveal that high-temperature microbial mats produce methionaquinones (MTK). Chloroflexus-mixed mats had menaquinone with significant amounts of MTK or plastoquinone 9. Biomats exposed to sunlight were found to be all cyanobacterial mats.

Differences in quinone profiles between the enhanced biological phosphate removal process (EBPR) and standard activated sludge systems are minimal. This was found in a study aimed at reexamining bacterial community structures in both plant scale and laboratory scale activated sludge reactors for EBPR, using respiratory quinone profiles. Ubiquinone with eight isoprene units, belonging to the class Proteobacteria, were the most abundant group in the EBPR sludge and the standard activated sludge, followed by members of the class Actinobacteria.

The community structure of pink-colored microbial mats naturally occurring in a swine wastewater ditch is studied by culture-independent biomarker and molecular methods as well as by conventional cultivation methods. The results demonstrate that the microbial mats are dominated by the purple nonsulfur bacteria of the genera Rhodobacter and Rhodopseudomonas, and the bioavailability of lower fatty acids in wastewater is a key factor allowing the formation of visible microbial mats.